Spring wound timer and cam mechanism

ABSTRACT

A spring wound timer apparatus is provided including a main spring and a mainshaft with two support plates for positioning a gear train mounted on shafts journaled in the plates, the spacing of the shafts being substantially equidistant from adjacent shafts along a curvilinear line on the plate. In addition, a cam assembly and stop mechanism operates in conjunction with the timer to cooperate with a control means such as a mechanical or electrical switch. The cam assembly includes a pair of cam members with the stop adapted to engage the periphery of the cams permitting gradual start-up of the timing cycle and a quick shutoff of the cycle.

United States Patent Dewhurst [54] SPRING WOUND TIMER AND CAM MECHANISM [72] Inventor: Paul E. Dewhurst, Bristol, Conn.

[73] Assignee: Kinetic Science Corporation, Me-

.riden, Conn.

[22] Filed: May 21, 1971 21] Appl. No.: 145,829

[56] References Cited UNITED STATES PATENTS 12/1951 Darnell ..58/2ll13 X 2,977,749 4/l96l Meyer .J 2,913,048 4/1959 Laviana ..58/2l.l3 X

7/l97l Draghi ..58/2l.l3

' Primary Examiner-Richard B. Wilkinson Assistant Examiner-Lawrence R. Franklin Attorney-Curtis, Morris 8!. Safford [57] ABSTRACT A spring wound timer apparatus is provided including a main spring and a mainshaft with two' support plates for positioning a gear train mounted on shafts journaled in the plates, the spacing of the shafts being substantially equidistant from adjacent shafts along a curvilinear line on the plate. In addition, a cam assembly and stop mechanism operates in conjunction with the timer to cooperate with a control means such as a mechanical or electrical switch. The cam assembly includes a pair of cam members with the stop adapted to engage the periphery of the cams permitting gradual start-up of the timing cycle and a quick shut-off of the cycle.

3 Claims, 9 Drawing Figures PATENTEDnsc 5 I972 3.704.581

sum 1 or 3 INVENTOR.

P404 z. DWHUR$7 times, length of stove and/or range' cooking durations,. operating periods for sunlamps,and manyother uses in various fields which are "well known tothose skilled in the art. As far as itis presently-known, heretofore it has been the generallyestablishedpractice to'design each timer apparatus and stop mechanism for the particular use andtimeperiod. to whichjthe timer and/or stop is to apply. This hasrequired more or less customdesign of the geartrains, the timer mounting plates for positioning the gears and the'stop mechanism.

Accordin gly,.it is'an object of the presentinvention to provideja timer constructionv with simplicity of design, multiple'uses of parts as well as a-flexibility for designingvarious timeranges so asto give a simplicity of product designand a reduction in manufacturing' costs.

;.It is a further object of the present invention to pro-' vide a cam and stop mechanism whichwill permit sure and accurate transfer of rotary motion to linear-motion with the outward motionof the cam follower being gradual and the returnfmotion'beingsudden. Still a further object is to provide such a cam and stop mechanism which is accurate and, yet, inexpensive to manufacture and easily coordinate'd for-use with a mechanical timer and other'control means. 4 I BRIEF SUMMARY or. T na INVENTION The presentinvention provides a timer which isrela- 'tivelysmall-in size, utilizing a runaway "type of escapementwith mounting holes for thegear train arranged around anzarc from the main shaft or gear, so that gears may be addedor removed to adapt a standardgear arrangementtoa particular elapsed time requirement for a selected application. The arrangement of using similar gears in the. gear train permits standardized plates with a maximum numberof mounting holes to be provided and used interchangeably with elapsed time arrangements requiring a few gears and those which require several gears for a longer running period.

, moved linearly to influence a control means of any well-known type, for example an electrical switch controlling the driving motor for a small appliance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top view of a timer mechanism in accordance with the present invention;

FIG. 2 is a side or back view of a timer mechanism in accordance with the present invention, showing the FIG. 5 is an enlarged sectional view along lines 55 of FIG. 4; I 1 j FIG. 6 is the first of four sequential views showing the relationship between the cam assembly and the stop mechanism, the position in this figure being the stop Y DESCRIPTION OFTHE ILLUSTRATED EMBODIMENT Referring to the drawings and to FIGS. 1 through 5 in particular, a timer assembly 10 is shown for use with a cam assembly and stop mechanism generally indicated as 12. The timer assembly is provided with a pair of movement plates 14 and 16 which arespaced apart by a pair-of pillars 18 and .20. In each of the mounting plates 14 and 16, a series of mounting holes 22 and 24 are provided. The holes 22 are advantageously arranged along a curvilinear line on the plates 14 and 16, each a hole being at substantially the same radial distance from the center of a main shaft hole 26. In addition each hole 22 is substantially equidistant fromthe adjacent holes 22. I

The second row of holes 24 is also laid out along a second curvilinear line with each hole substantially equidistant from its adjacent holes and substantially the same radial distance from thecenter hole 26.

In the illustrated embodiment, amain shaft 28 is provided and inserted through the'hole 26 in the movement plates' l4 and 16. A main spring 30 is coiled around the main shaft 28 with theinner end of'the coil attached to an anchor 32 on the main shaft 28-. The other end of the main spring 30 is attached to the spacing pillar 18 by any suitable means.

Also fixedly mounted on the main shaft 28 is a main gear 34. The main gear 34 meshes with the pinion of a first gear 36 which is mounted in one of the opposed sets of holes 22 in plates 14 and 16.:The first gear 36 in turn meshes with the pinion, of a gear 38 mounted in one set of holes 24 along the. secondcurvilinear line. The gear 38 combines with three additional gears 40, 42 and 44 to form a gear train, all these gears being mounted in the holes 24.

Gear 44 meshes with the pinion 46 of an escapeflexibility in selecting the total elapsed time required for a particular application with a minimum number of gears and mounting plates. By this means it is possible to customize a particular timer construction without the necessity of designing special parts.

In order to utilize the. timer, any suitable wind-up knob 58 may .be used which has a time indicator 60 thereon and which may be rotated through any number of positions on a time markin g scale 62. Of course the time scale will be determined by the gear train arrangement and the verge construction in accordance with practice well known to those skilled in the art.

The cam assembly 12 is mounted on a' U-shaped metal mounting bracket 64 which is in turn joined to the plate 14. End portions 66 and 68 of the bracket are fitted-over the spacing pillars 18 and 20, respectively, and the ends 70 and 72 of the pillars 18 and are formed or peened over the end portion 66 and 68 to fix the assembly bracket 64 in place. The bracket 64 further includes vertical flanges 74 and 76'which are connected together by a web 78. A slide member 80 is provided with mounting grooves 82 on each side thereof. The slide 80-is preferably made from a hard-wearing, self-lubricating material such as a plastic identified by the trademark Delrin and sold by E. I. duPont. A pair of fingers 84 depend from 78 and are fitted into the mounting grooves 82. In addition, a .pair of side guides 86 also depend from the web 78 and cooperate with the fingers 84 to provide a slide guide or path for the slide 80.

A partial bore 88 is provided in the slide 80, the bore being aligned generally with the mounting grooves 82. A coil spring '90 is placed in the bore 88"and reacts against a plate 92 connected to the web 78. Depending from the body portion of the slide 80 is a stop 49 which acts as a cam follower and cooperates with a cam assembly 96, whereby rotary motion of the main shaft 28 is transferred to linear motion of the slide 80.

The cam assembly 96 is comprised of a cam plate 98 which is journaled in fixed relationship to the main shaft 28. Overlying the cam plate 98 is a flip-flop plate 100 which is loosely positioned about the main shaft 28. The cam plate 98 is advantageously formed of a self-lubricating plastic of material similar to the slide 80. The flip-flop may be stamped from any suitable metal such as aluminum or steel.

. A shoulder of crescent shape 102 isprovided on the cam plate 98. The shoulder 102 has two straight limit edges 104 andl06. In addition, a recess 1080f substantially wide extent at the periphery of the plate 98 is also provided.

A nose portion 110 on the stop 49 acting as a cam follower engages the, recess 108 when the timer and cam mechanism isin the stop or at-rest position. This relationship is clearly shown in FIG. 6.

FIGS. 6 through 9 show the sequential relationship between the cam assembly and the stop 49 from an atrest condition to full wind up.

The flip-flip 100 has a cam arm 112 and the outer peripheral edge 114 of arm 112 extends beyond the outer peripheral edge-116 of the came plate 98. In addition, a recess 118 is provided in the periphery of flipflop 100 and the peripheral opening of the flip-flop opening 118 is substantially less than the peripheral opening of recess 108 in the cam plate 98.

Flip-flop 100 also has a limit arm 120 with a substantially vertical stop face 122.

Whenthe main shaft 28 is rotated by the knob 58, the nose portion 110 of stop 49 bears against the side edge of recess 108 until cam arm 1120f flip-flop 100 engages the limit edge 104 of shoulder 102. When that occurs, the nose portion 110 then rides onto the outer periphery of 114 and, if rotation of the main shaft 28 continues, then onto the outer periphery 116 of cam plate 98 until the nose portion 110 contacts the limit stop 122 or arm 120. In the illustrated embodiment this permits the shaft 28 to be rotated through approximately 310 before movement is stopped by engagement with the limit stop 122.

While riding on the periphery of the cam assembly, the nose portion 110 carries the slide to a position indicated in FIG. 5 by the phantom lines 80. When the unwind cycle is just about to be completed, the nose portion is riding on the peripheral edge of the flipflop as shown in FIG. 9. As the fixed cam plate 98 continues to rotate, the flip-flop is carried with it and at the point where the nose portion 110 meets the recess 118 there is a sharp movement of the slide 80 causing a quick stop to the cam mechanism and sharp movement of the slide 80.

Thus, in this manner it is possible to have slow startup of the slide 80 and a rapid shutdown. This is particularly effective in those situations where the slide 80 will be used to open and close an electrical switch, where quick movement prevents damage to contact points, or even in those cases where it will open or close a mechanical switch and sharp responses are desired.

It should be noted that the extent of periphery 114 on flip-flop 100 beyond periphery 116 on cam plate 98 advantageously permits the sharp closure. This is due to the fact that the stop 49 acting as a cam follower suddenly moves from periphery 116 into recess 118.

The limit arm is provided with a second recess 124 which serves as a manual position in which the switch or other control device connected to the timer may be manually operated without the timer running. The concept of the manual position is well known to those skilled in the art.

A button or other appendage 128 may be fixed to the slide 80 to engage the particular device which is to be controlled by the timer.

To facilitate setting of the desired time cycle by rotation of the main shaft, a fraction plate 130 is provided about the main shaft 28 on one side of the gear 34 and a spring clutch 132 is provided on the opposite side. Inasmuch as the gear train will only run in one direction, i.e., the unwind direction, the clutch permits the main shaft to be rotated to wind the coil spring without moving the gear train.

To keep the cam assembly 96 in as minimum a friction relation with the plate 14 as possible, a spring washer 126 is provided which has an undulating shape providing but three bearing points on each surface it contacts.

It will be apparent to those skilled in the art that the foregoing description of the illustrated embodiment may be modified and yet be within the scope of the following claims.

What is claimed:

1. A spring wound timer apparatus, the running period of which is adaptable to be increased or reduced, comprising:

a pair of spaced apart mounting plates,

a coiled main spring positioned between said plates having one end fixed in place and the other end connected to a main shaft, said main shaft positioned substantially normal to said plates and adapted to be rotated in one direction to wind said spring and to rotate in the opposite direction when the spring unwinds,

a main gear mounted on said shaft and rotatable therewith,

escapementmeans forming a timing control system,

a gear train interconnecting said main gear and said escapement means, said gear train comprising a plurality of secondary gears, each having driven teeth and driving teeth, said plurality of gears mounted on shafts journaled in said mounting plates such that each gear has substantially the same radial distance from said main shaft to the closest driven teeth thereof,

a plurality of bearing holes in said mounting plates located along a line of constant radius from said shaft, and

an intermediate gear journaled in a selected one of said bearing holes for operatively connecting said main gear to a selected one of said secondary gears, whereby the running period of the timer may be increased or decreased by selecting the desired bearing holes and adding or reducing the number of gears in the gear train.

2. A spring wound timer apparatus as defined in claim 1 and further including a cam assembly to cooperate with a control means, said cam assembly comprising a first cam member fixedly mounted on the main shaft, a second cam member freely mounted on said main shaft and adapted to be rotated by said first cam member, a slide stop adapted to engage the periphery of said cam assembly when said main shaft rotates in timed sequence under the influence of the timing system, said slide stop movable to engage recesses in said cam members and thereby influence said control means.

3. A spring wound timer apparatus as defined in claim 1 wherein said gear train is comprised substantially of a series of gears and pinions wherein the gears are substantially of the same diameter and the pinions are of alternating common sizes. 

1. A spring wound timer apparatus, the running period of which is adaptable to be increased or reduced, comprising: a pair of spaced apart mounting plates, a coiled main spring positioned between said plates having one end fixed in place and the other end connected to a main shaft, said main shaft positioned substantially normal to said plates and adapted to be rotated in one direction to wind said spring and to rotate in the opposite direction when the spring unwinds, a main gear mounted on said shaft and rotatable therewith, escapement means forming a timing control system, a gear train interconnecting said main gear and said escapement means, said gear train comprising a plurality of secondary gears, each having driven teeth and driving teeth, said plurality of gears mounted on shafts journaled in said mounting plates such that each gear has substantially the same radial distance from said main shaft to the closest driven teeth thereof, a plurality of bearing holes in said mounting plates located along a line of constant radius from said shaft, and an intermediate gear journaled in a selected one of said bearing holes for operatively connecting said main gear to a selected one of said secondary gears, whereby the running period of the timer may be increased or decreased by selecting the desired bearing holes and adding or reducing the number of gears in the gear train.
 2. A spring wound timer apparatus as defined in claim 1 and further including a cam assembly to cooperate with a control means, said cam assembly comprising a first cam member fixedly mounted on the main shaft, a second cam member freely mounted on said main shaft and adapted to be rotated by said first cam member, a slide stop adapted to engage the periphery of said cam assembly when said main shaft rotates in timed sequence under the influence of the timing system, said slide stop movable to engage recesses in said cam members and thereby influence said control means.
 3. A spring wound timer apparatus as defined in claim 1 wherein said gear train is comprised substantially of a series of gears and pinions wherein the gears are substantially of the same diameter and the pinions are of alternating common sizes. 